1. Field of the Invention
The present invention relates to a propeller system for installation in aircrafts, and more particularly to a pitch control apparatus for a variable pitch propeller.
2. Description of the Prior Art
In Japanese Patent Early Publication No. 60-76499, there has been proposed a pitch control apparatus for a variable pitch propeller wherein the pitch angle and rotation speed of the propeller are controlled on a basis of data indicative of Mach number, flight height, atmospheric temperature, output power of the aircraft engine in flight to maximize the operation efficiency of the propeller. In the pitch control apparatus, only the performance data of the propeller is used to enhance the operation efficiency of the propeller without any consideration to the engine characteristic. Since a thrust force acting on the aircraft is represented by a product of the engine output power and the operation efficiency of the propeller, a maximum thrust force would not be obtained even if only the operation efficiency of the propeller in flight was maximized under control of the opening degree of the engine throttle.